In the operation of a loom having a shuttle which is moved back and forth by hinged picker sticks, it is common practice to swing each picker stick by means of a reciprocating mechanism which is connected to the picker stick by a U-shaped lug strap. The picker stick engages the bight of the strap and the legs of the strap are attached to the reciprocating mechanism. During the operation of the loom at a high rate of speed, a large number of forces acting in various directions are received and absorbed by the lug strap, so that the lug strap is a portion of the loom that falls into a state of disrepair more often than other parts. Shutting down the loom to provide it with a new lug strap is an economic waste, not to speak of the expense of the millwright's time in making the changeover. In other words, not only is an expense involved when it is necessary to provide new lug straps at frequent intervals, but the downtime and labor involved are also appreciable. For that reason, a considerable amount of experimental work has been done to develop the ideal lug strap. The lug straps in the older looms were made of leather and, at slow pick speeds, this material has many advantages. One advantage is that (at least at one time) it was fairly inexpensive. As pick speeds increased over the years, due to the development and improvements in other parts of the loom, it was found necessary to manufacture lug straps of a more sophisticated nature. One fruitful line of investigation involved the use of woven webbing as a material for the lug strap; this material had the advantage of being able to absorb and deaden shock forces and vibrations. With the development of modern polymeric materials, certain advantages have been obtained in impregnating the fiber of the webbing with polymers.
While the impregnation of the webbing with a polymer reduces the wear and prolongs the life of the strap, other difficulties have arisen. For one thing, it has always been the practice to form the bight of the lug strap in a semi-circular form. It has been found that, when impregnated webbing is used in this shape for the lug strap, the striking of the arc by the picker stick (which is of generally rectangular cross-sectional form) results in extreme distortion of the shape of the strap. This not only causes a change in the length of the strap (and therefore of the adjustment of the loom), but also causes certain actions that tend to destroy the strength of the lug strap. More specifically, the encounter of the sharp corners of the rectangular picker stick with the curved surface of the lug strap produces a high concentration of force. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the invention to provide a lug strap for a loom, which strap retains its dimensional integrity throughout a long life of service.
Another object of this invention is the provision of a lug strap which does not require adjustment or replacement for long periods of time.
A further object of the present invention is the provision of a lug strap which wears very little under the action of the picker stick and which makes relatively little noise.
It is another object of the instant invention to provide a lug strap which can be readily manufactured from inexpensive, readily-available materials and which is capable of a long life of useful service with a minimum of maintenance.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.